class Person {}

function mixinRunner(BaseClass) {
  class NewClass extends BaseClass {
    running() {
      console.log("running");
    }
  }
  return NewClass
}

function mixinEater(BaseClass) {
  class NewClass extends BaseClass {
    eating() {
      console.log("eating");
    }
  }
  return NewClass
}

class Student extends Person {}

var NewStudent = mixinEater(mixinRunner(Student))
var ns = new NewStudent()
ns.running()
ns.eating()